Pull chain operator for rotary switch shaft

ABSTRACT

An internally threaded tube forming a supporting hub for the device is mounted on the rotary switch shaft in a socket for a three-way light bulb in place of the conventional knob on the switch shaft. An eccentric drum is rotatably mounted on the tube and a ratchet gear in the drum is fixedly mounted on the tube. A pawl in the drum engages the ratchet gear. A pull chain on the drum rotates the switch shaft through fractional revolutions to switch the light circuit to low, medium, high and off in successive manipulations. A counterweight in the drum returns the drum and pull chain to starting position after each actuation of the switch.

United States Patent Marshall, Jr.

[54] PULL CHAIN OPERATOR FOR ROTARY SWITCH SHAFT [72] Inventor: RobertMarshall, Jr., 3425 NE. Ainsworth, Portland, Oreg. 9721 l [22] Filed:Jan. 21, 19'" 2| Appl. No.: 108,526

[52] U.S.Cl. ..200/l72 R, 200/l6l,200/5l.l5 511 int. c|...- .3010 3/10[58] Fleldol'search ..200/l72R,5l.l5,l6l

[56] References Cked UNITED STATES PATENTS 984,053 2/l9ll Weber, Sr ..200/l6l 2,595,851 5/1952 l-lolzapfel ..-..200/l6l X [451 Feb. 15, 1972Primary Examiner-David Smith, .I r. Attorney-Lee R. Schennerhom [S7]ABSTRACT An internally threaded tube forming a supporting hub for thedevice is mounted on the rotary switch shaft in a socket for a three-waylightbulb in place of the conventional knob on the .switch shaft. Aneccentric drum is rotatably mounted on the tube and a ratchet gear inthe drum is fixedly mounted on the tube. A pawl in the drum engages theratchet gear. A pull chain on the drum rotates the switch shaft throughfractional revolutions to switch the light circuit to low, medium, highand off in successive manipulations. A counterweight in the drum returnsthe drum and pull chain to starting position after each actuation of theswitch.

9Claims,6DrawingFigures PATENTEDHBY 5 m2 3, 63 052 INVE/VTDR ROBERTMARSHALL JR.

This invention relates to a pull chain operator for a rotary switchshaft and is of particular advantage in connection with conventionalsockets for three-way light bulbs which are switched in successive 90rotations of the switch shaft to low, V

medium, high and ofi positions.

Lights of this type are often used in floor lamps where the light socketswitch is out of reach of a person sitting in a chair by the lamp orlying in a bedalongside the lamp. Pull chain sockets heretofore providedfor three-way lamps have been relatively complicated and expensive andcannot readily be substituted for the more common rotary knob .type ofsocket switch usually furnished in floor lamps.

An accessory type of device has been proposed heretofore to convert arotary knob switch into a pull chain switch but in this case a springwas utilized to return the pull chain after each operation of theswitch. The use of a spring for this purpose necessitates a stationaryanchor for one end of the spring and this requires either a special formof light socket or some modification of a conventional socket whichcannot be accomplished readily by the ordinary user.

Objects of the invention are, therefore, to provide a pull chainoperator for a rotary switch shaft which may be readily applied by theuser to a common type of electric switch, to provide a pull chainattachment which may be installed on the socket of a three-way lightbulb by merely unscrewing the switch knob, to provide a pull chain Ioperator of the type described which does not require a springreturn-for the pull chain and to provide a pull chain operator havingagravity actuated counterweight to return the pull chain.

SUMMARY OF THE INVENTION The present device comprises, essentially,merely a tubular hub for mounting on a threaded switch shaft after theconventional knob has been unscrewed and a drum for the pull chainrotatably mounted on the tubular hub. Fixedly mounted on the tubular hubis a ratchet gear which is engaged by a pawl on the drum. Successivepulls on the chain thereby rotate the switch shaft through quarter turnsto low, medium-high and off positions, the chain being raised tostarting position after each switch actuation by a counterweight in thedrum.

The invention will be better understood and the foregoing and otherobjects and advantages will become apparent from the followingdescription of certain preferred embodiments illustrated on theaccompanying drawing. Various changes may be made in thedetails ofconstruction and arrangement of parts and certain features may be usedwithout others. All such modifications within the scope of the appendedclaims are included in the invention.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an elevation view of athree-way light bulb and socket equipped with a pull chain operatorembodying the invention;

FIG. 2 is a view on the line 2-2 in FIG. 1 with parts broken away,showing the device in normal rest position;

FIG. 3 is a view on the line 33 in FIG. 2;

FIG. 4 is a view similar to FIG. 2 showing the parts in actuatedposition;

FIG. 5 is a view similar to FIG. 2 showing a modification; and

FIG. 6 is a view similar to FIG. 2 showing a further modification.

DESCRIPTION OF TI'IE PREFERRED EMBODIMENTS FIG. 1 shows theupper end ofa floor lamp having a common form of three-way light bulb 10 and socket11 with a rotary switch shaft 12 which is threaded to normally receive aknobQWhen the operator is facing the knob, a first quarter turn to theright rotates the switch shafi to'low position, a

chain 31 are referred to collectively as a pull chain. 5

second. quarter turn rotates it to medium position, a third quarter tumrotates it to high position and a fourth quarter tum rotates it to offposition. In FIG. I the conventional knob has been replaced by a firstembodiment of the present device which is indicated in its entirety bythe numeral I5.

The device 15 in FIGS. 1 to 4' comprises, essentially, a drum 16 mountedfor rotation on a hub 17. Hub 17 preferably comprises a tube which isinternally threaded in its inner end at 18 to fit the projectingthreaded end of the switch shaft 12. For a purpose which will presentlybe explained, the outer end of tube 17 is provided with an internalleft-hand thread to receiv a left-hand threaded screw 20 and lock washer21.

Disposed within the drum 16 a ratchet gear 22 is fixedly mounted on tube17 for engagement on its upper side by a pawl 23 which is pivotallymounted on a pin 24 in the drum 16. Pawl 23 has an elongated weightedend 25 extending away from the pivot pin 24 above ratchet gear 22.Adjacent the pivot pin 24 the drumhas an anchor pin 29 for one end of alightweight flexible plastic cord or band 30 which is connected at itsother end to the pull chain 31. A portion of thedrum has side flanges 26to retain the band 30 on the drum. Band 30 and On the opposite side ofthe drum from pawl 23 the drum contains a lead counterweight 32. Inorder to make the device as small and inexpensive as possible, the drumis preferably eccentrically mounted on tube 17 so that its lower side inFIG. 2 is considerably farther from the axis of rotation than its upperside. With a given diameter of drum, this arrangement gives thecounterweight greater mechanical advantage for lifting the band 30 andchain 31.

This advantage is enhanced by using only a short length of metal chain31 and connecting it to a length of the very lightweight plastic band 30which materially reduces the load that must be lifted by thecounterweight. Also, the band 30 exhibits less tendency to jump out ofthe pulley groove between side flanges 26 than does a metal chain. It isdesirable to include at least a short length of chain for the benefit ofpersons unfamiliar with the device. People are accustomed to usingsimple two-position on and off pull chain switches whereas the purposeof a hanging end of plastic band might not be apparent.

The parts are shown in normal rest position in FIG. 2 whereincounterweight 32 is displaced from bottom position by an angle whichbalances the weight of band 30 and pull chain 31. The arcuate weightedend 25 of pawl 23 overhangs ratchet gear 22 and holds the pawlinengagement with the upper side of the ratchet gear. When chain 31 ispulled downward in the direction of the arrows, drum I6 is rotatedcounterclockwise a quarter turn to its FIG. 4 position thereby rotatingswitch shaft 12 to its next switching position. Counterweight 32 hasmoved upward where it is in a position to rotate the drum clockwise backto its FIG. 2 position as soon as the pull chain is released. Duringthis return movement, pawl 23 overrides the sloping teeth on the ratchetgear which is then held stationary by the switch mechanism in socket II.

The purpose of screw 20 is to provide means for removing the device fromthe lamp socket. There is ordinarily insufficient space beiween socket11 and drum 16 to permit a firm grasp of tube 17 by the fingers and itis desired to make the device both attachable and removable withoutspecial tools. By applying a screwdriver to the slot in the screw 20,the tube 17 may be turned clockwise in FIG. 2 to unscrew the tube fromswitch shaft 12.'A screwdriver is not necessary in applying the devicesince pawl 23 makes it possible to turn tube 17 counterclockwise in FIG.2 by merely rotating the drum 16 itself. Counterclockwise rotation inFIG. 2 is clockwise rotation to an operator facing the end of switchshaft 12 which is equipped with right-hand threads.

Since the pull chain drum is returned by a counterweight instead of aspring, the present device is entirely independent of the shell ofsocket 11 and the socket is not utilized to provide a stationary springanchor. With a spring return, a special form modified in some way.

The modification in FIG. 5 is similar to the construction just describedexcept in this case the pawl 35 is pivotally mounted on a pin 36 whichis on the underside of the axis of rotation in rest position. This pawlhas a weighted end 37 projecting on the opposite side of pivot 36 toraise the pawl into engagement with the under side of the ratchet gear22. In order to make the device small and compact, a portion of thecounterweight must be relieved to accommodate the pawl but this is not adisadvantage because with the pawl in this position, its weightsupplements the weight of the counterweight to provide useful returntorque to the drum. FIG. 5 shows the device in normal rest position. Inoperation, the drum [6 rotates a quarter turn counterclockwise as inFIG. 4.

The modification in FIG. 6 is similar to the foregoing embodimentsexcept that in this case the pawl 40 is a spring pawl rather than agravity actuated pawl. This pawl is a light cantilever spring arm havingan end portion 41 mounted on an internal lug 42 in the drum 16. FIG. 6shows the parts in rest position and the operation is the same asdescribed above in ble with said ratchet gear, a pull chain on said drumarranged to rotate the drum a fraction of a turn in a direction tooperate the switch, and a counterweight on said drum arranged to rotatesaid drum in the opposite direction after operation by said pull chain.

2. A switch operator as defined in claim 1, said pawl being gravityactuated into engagement with said ratchet gear.

3. A switch operator as defined in claim 1, said pawl being springactuated into engagement with said ratchet gear.

4. A switch operator as defined in claim 1, said drum being eccentric tosaid hub and shaft.

5. A switch operator as defined in claim 1, said pull chain including aflexible band wrapped on said drum.

6. A switch operator as defined in claim 1, said ratchet gear, pawl andcounterweight being contained in said drum.

7. A switch operator as defined in claim I, said hub member comprisingan internally threaded tube.

8. A switch operator as defined in claim 7, one end of said tube beingadapted for threaded connection with said switch shaft, and a screw inthe opposite end of said tube having a screwdriver slot for turning saidtube on said shaft.

9. A switch operator as defined in claim 1, said hub member comprisingan internally threaded tube for threaded engagement with said switchshaft, said drum being eccentric to said tube, and said ratchet gear,pawl and counterweight being contained in said drum.

i t I i

1. A pull chain operator for a rotary switch shaft comprising a hubmember adapted for mounting on said shaft, a ratchet gear fixedlymounted on said hub member, a drum rotatably mounted on said hub member,a pawl on said drum engageable with said ratchet gear, a pull chain onsaid drum arranged to rotate the drum a fraction of a turn in adirection to operate the switch, and a counterweight on said drumarranged to rotate said drum in the opposite direction after operationby said pull chain.
 2. A switch operator as defined in claim 1, saidpawl being gravity actuated into engagement with said ratchet gear.
 3. Aswitch operator as defined in claim 1, said pawl being spring actuatedinto engagement with said ratchet gear.
 4. A switch operator as definedin claim 1, said drum being eccentric to said hub and shaft.
 5. A switchoperator as defined in claim 1, said pull chain including a flexibleband wrapped on said drum.
 6. A switch operator as defined in claim 1,said ratchet gear, pawl and counterweight being contained in said drum.7. A switch operator as defined in claim 1, said hub member comprisingan internally threaded tube.
 8. A switch operator as defined in claim 7,one end of said tube being adapted for threaded connection with saidswitch shaft, and a screw in the opposite end of said tube having ascrewdriver slot for turning said tube on said shaft.
 9. A switchoperator as defined in claim 1, said hub member comprising an internallythreaded tube for threaded engagement with said switch shaft, said drumbeiNg eccentric to said tube, and said ratchet gear, pawl andcounterweight being contained in said drum.